Field of the Invention
The disclosure generally relates to an antenna structure, and more specifically, to a multiband switchable antenna structure for use in a mobile device.
Description of the Related Art
With the progress of mobile communication technology, mobile devices, for example, portable computers, mobile phones, tablet computers, multimedia players, and other hybrid functional portable electronic devices, have become more common. To satisfy the needs of users, mobile devices usually can perform wireless communication functions. Some functions cover a large wireless communication area; for example, mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some functions cover a small wireless communication area; for example, mobile phones using Wi-Fi and Bluetooth systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz.
A conventional design often uses a metal element with a fixed size as an antenna body of a mobile device. The metal element has a length of 0.5 or 0.25 wavelength corresponding to the desired frequency band. As a result, a conventional antenna design merely covers a single frequency band or a narrow frequency band, and it cannot meet the requirements of a current mobile device operating in multiple or wide frequency bands.